Many portable computers (laptop, notebook, netbook and the like) incorporate wireless communication devices that operate in more than one frequency band and more than one operating mode. Some examples of operating modes include GSM, CDMA, WCDMA, LTE, EVDO—each in multiple frequency bands (CDMA450, US cellular CDMA/GSM, US PCS CDMA/GSM/WCDMA/LTE/EVDO, IMT CDMA/WCDMA/LTE, GSM900, DCS), short range communication links (Bluetooth, UWB), broadcast media reception (MediaFLO, DVB-H), high speed internet access (UMB, HSPA, 802.11a/b/g/n, EVDO), and position location technologies (GPS, Galileo). Therefore, with each of these modes in a wireless communication device embedded within a portable computer, the number of radios and frequency bands is incrementally increased. Furthermore, the complexity and design challenges for a wideband antenna supporting each frequency band as well as potentially multiple wideband antennas operating simultaneously (for receive and/or transmit diversity) may increase significantly. The number of radio frequency connections or cables between the wideband antennas and associated wireless communication device(s) embedded within the portable computer may also be a significant cost and design challenge.
One traditional solution for a wideband antenna is to combine multiple single-band antennas in parallel. The main disadvantage of this design technique is the large size required to accommodate multiple antennas. Another common solution for a wideband antenna is to manipulate the multiple resonant frequencies of a single antenna. The main drawback of this design technique is that the operating frequency bands must be close in frequency to the resonant harmonic frequencies of the antenna structure. Another common solution for a wideband antenna is to design a complex folded 2-d or 3-d structure that resonates in multiple frequency bands. Controlling the wideband antenna input impedance as well as enhancing the wideband antenna radiation efficiency (across a wide range of operative frequency bands) is restricted by the geometry of the wideband antenna and a matching circuit between the wideband antenna and the radio signal paths(s) from the wireless communication device. Often when this design approach is taken, the geometry of the wideband antenna is very complex and the physical area/volume of the wideband antenna increases.
With the limitations on designing wideband antennas with high antenna radiation efficiency and associated matching circuits, another solution is utilizing multiple antenna elements to cover multiple operative frequency bands. In a particular application, a wireless communication device embedded within a portable computer may include three frequency bands—US PCS, GPS, and Bluetooth. In this instance, separate radios may utilize one antenna for each operative frequency band (each antenna operates in a single radio frequency band). However, separate antennas may be required to allow simultaneous operation of a wide-area network link (such as CDMA at US Cellular 800 MHz or US PCS 1900 MHz) along with position location (GPS at 1.575 GHz) and wireless audio interface to a headset (Bluetooth at 2.4 GHz). In this particular design example, individual antennas must also be electrically isolated from each other to allow simultaneous operation.
Another design example may include 802.11n, where multiple (2, 3, or 4 normally) wideband antennas may operate in the same frequency at the same time to achieve higher data throughput. The isolation (coupling) required between wideband antennas in 802.11n is less than is required for multi-mode operation (CDMA, GPS, Bluetooth for example). Unfortunately in both examples, incorporating multiple antennas is significant design challenge and potential impacts include the additional area/volume and the additional cost of multiple (single-band or wideband) antenna elements.
There is a need for a wideband antenna with improved radiation efficiency across a broad range of operative frequencies for wireless communication devices embedded within portable computers. There is also a need for multiple wideband antennas within portable computers to allow simultaneous operation in one or more frequency bands.
To facilitate understanding, identical reference numerals have been used where possible to designate identical elements that are common to the figures, except that suffixes may be added, when appropriate, to differentiate such elements. The images in the drawings are simplified for illustrative purposes and are not necessarily depicted to scale.
The appended drawings illustrate exemplary configurations of the disclosure and, as such, should not be considered as limiting the scope of the disclosure that may admit to other equally effective configurations. Correspondingly, it has been contemplated that features of some configurations may be beneficially incorporated in other configurations without further recitation.